Time Dilation

 

Time dilation is a phenomenon predicted by Einstein’s theory of relativity, where time passes at different rates depending on your speed or gravitational field strength.

There are two main types:

---

🌀 1. Special Relativity – Velocity Time Dilation

When an object moves close to the speed of light (c), time slows down for it compared to someone at rest.

Formula:

t' = \frac{t}{\sqrt{1 - \frac{v^2}{c^2}}}

• : time experienced by the moving observer
• : time measured by a stationary observer
• : velocity of the moving object
• : speed of light (~3×10⁸ m/s)

Example:
If you travel at 99.9% the speed of light, 1 hour for you could be 44.7 hours for someone on Earth.

This is why astronauts moving very fast age slightly slower — this effect is called kinematic time dilation.

---

🌌 2. General Relativity – Gravitational Time Dilation

Time also slows down near strong gravity (like black holes) because gravity warps spacetime.

Formula:

t' = t \sqrt{1 - \frac{2GM}{rc^2}}

• : gravitational constant
• : mass of the object (e.g., black hole)
• : distance from the center of mass
• : time experienced near the mass
• : time far away from the mass

Example:
If you orbit close to a black hole, a few minutes for you could equal years for someone far away — like in Interstellar.

---

⏳ Key Insight

Time dilation means time is not absolute — it depends on motion and gravity.
Every observer has their own "clock," and relativity tells us how they compare.

---